Cascaded Raman and Intermodal Four-Wave Mixing in Conventional Non-Zero Dispersion-Shifted Fiber for Versatile Ultra-Broadband Continuum Generation

Abstract

We demonstrate an efficient ultra-broadband supercontinuum generation in telecom-grade optical fiber by pumping Q-switched subnanosecond laser pulses (0.77 ns) at 1064 nm in the normal dispersion region of the fiber. The fiber supports several spatial modes at this pump wavelength. Multiple sidebands with six Raman stokes spanning over more than 1100 nm (starting well below 600 nm and extending beyond 1700 nm) are generated using very low input pump power (average 57 mW). Theoretical analysis shows that cascaded Raman and cascaded intermodal four-wave mixing processes can account for the generation of multiple sidebands. We also demonstrate that the modal composition of the input pump profile can provide an extra degree of freedom in tailoring the multiple Raman peaks in the output spectrum.